Opening and Closing Language Injections in the Editor

To open a language injection in the editor:

In the editor, place the cursor within the string literal that represents the language injection of interest.

To show the available intention actions, do one of the following:

Click the yellow bulb .

Press Alt+Enter.

To select the Edit <Injected Language> Fragment option, do one of the following:

Click this option.

Use the Up and Down arrow keys to navigate to the option,
and then press Enter to select it.

You can open a number of language injections in separate editors, and copy code fragments from one editor to another.
However, as soon as you start modifying the code in one of the editors, all the rest of the editors close automatically.